Superheater



J. A. M GREW July 18, 1933.

SUPERHEATER Filed Sept. 3, 1930 2 Sheets-Sheet l July 18, 1933. J. A. McGREW 1,918,654

SUPERHEATER Filed Sept. 5, 1930 2 sheets sheet 2 Patented July 18, 1933 "UNITED STATES v PATENT OFFICE JOHN A. meanwor ALBANY, NEW YORK "S'UPERHEATEB Application filed September 3, 1930; Serial no, 479,572.

of the fire bed so that such gaseous products do not pass directly into the fire tubes of the boiler but are caused to'fiow rearwardly over thebed of incandescent fuel to pass around the rear edge ofthe bafile or'arch before passing forwardly toward the fire tubes. By means of such arch constructionsmuch more perfectcombustion is brought about, any unurned combustible gases generated at the forward end of the grate being ignited and 1 consumed in their passage over the hot fuel bed. Firebox arch constructions of one type or another are now believed to be practically .indispensable in modern locomotive practice.

The most common type of arch comprises'a supporting structure which includes a plurality of parallel tubesextending in a generally diagonal direction, and refractory brick supported upon such tubes; the tubes being so disposed, and the refractory bricks being so positioned thereon, that an inclined,

substantially gas-tight screen is formed, having its lower and forward edge in contact with the inner throat sheets of the boiler shell at thefront end of the firebox, its higher rear ward edge somewhere near the center of the firebox (considering both the longitudinal and vertical dimensions thereof) and its lateral edges in contact with the side sheets of the firebox. The refractory bricks are maintained in position usually merely by the force of gravity. In the operation of a locomotive a great many of these bricks are burned out and need to be replaced at frequent intervals.

Since they are relatively expensive, the cost of upkeep of the average firebox arch is a material expense. I

It is also now generally accepted that the installation of a superheater greatly promotes the efiiciency of the modern locomotive, resulting in increased economy of coal and water consumption perton mile, and having also the advantages of increased boiler capacity without increased weight, reduced boiler pressures for the same engine output, and lowered costs of boiler maintenance; The super-heater. structure which is now most commonly employed, however, is rather complicated, involving the use of a superheater header of intricate design positioned in the smoke box of the locomotive, and of a large number of individual superheater pipes or units which extend rearwardly from the header "and are positioned within the fire tubes of the boiler. The construction is such that at regular intervals of time,the locomotive must be placed in a shop and dismantled to permit the complete removal of the superheater with its header and tubes for inspection and repair. Because of the complexity of the device, this involves a lengthy layoff of the engine, not to mention the very considerable 'labor and material costs involvedin such repair work.

The general object of the present invention is to provide a novel firebox arch construction for locomotive boilers which includes, as an element,a heating unit for super-heating steam already generated in the boiler. By combining these two structures, a numberof advantages are realized. In thiscase,'it is apparent that'the cost of installation of each is lowered; forexample, the number of fire bricks required'in the construction of the arch is greatly decreased, nearly all of the brick normally used in this construction being supplanted by the superheater unit which performs the function of bafiling the products of combustion in addition to its superheating function, and also the complicated header and pipe units of the superheaters of the fire tube type being replaced by simple and relatively inexpensive structure. Not only is there a great saving realized withrespect to original installation costs, but by means of my invention the cost of upkeep of both superheater andfireboxarch is decreased. Furthermore, by placing the superheater unit in the firebox a greater degree of superheating may be realized, the unitbeing in close proximity to the fire instead of being relatively remote therefrom, as in the case of a superheater installed in either the smoke box or the fire tubes of the locomotive.

A more specific object of the invention is to provide, in connection with a firebox superheater of the type described, means for rapidly eonducting the heat from the outer wall of the superheaterconduit to the center thereof, thus preventing the destruction of said wall and also eliminating from the center of the conduit, which is of relatively large diameter, the central core of steam of a relatively low degree of superheat which would otherwise be present in the stream of steam passing through the conduit.

7 Many further advantages of my improved construction will be apparent to one skilled in the art as its nature is more fully disclosed in'the following detailed description and in theaccompanying drawings in which one G111- bodiment of my invention is illustrated by way of example.

In the drawings: y x

Figure 1 is a longitudinal sectional view of a locomotive boiler illustrating the installation of my improved superheater and arch therein;

Figure 2 is a transverse sectional view taken on line 22 of Figure 1;

Figure-3 is a top plan view of my improved firebox superheaterunit, portions thereof be- 1n'g shown in section; v

Figure 4; is a longitudinal vertical sectional view taken on line 44: of Figure 3; and

Figure 5 is a transverse cross-sectional view taken on line 55 of Figure 3.

Referring to-the drawings, the boilershell of the locomotive is designated by thenumeral 10, the firebox by 1'1 ,'the smoke box by 12'and the steam dome by 13. The fire grate is omitted, as wellas other details of the boiler and locomotive in order, that the de tails of the present inventionrmay, be more clearly illustrated. r 1 I The, usual dry pipe leading from the steam dome'forwardly to the smoke box is indicated at 15 andis connected as at'16 with a header 17 which is adapted to take the place of the usual complicated:superheater header structure employedin the prior practice. The header l7 ispreferably formed of a single casting comprising an inlet chamber 18 and an outlet chamber 19. 'The forward end of this header is connectedv by 'means of'pipe 20 with the frontend throttle 21 which. is adapted to control the supply of steam passing through the pipes 22 to the cylinders (not shown) of the locomotive;

A. series of pipes or tubes 23 of relatively small diameter have their forward ends in communication"with the chamber18 of the header 17 and pass rearwardly through one within another row of fire tubes 27.

are connected to the combined arch and superheater "unit 25. A series of similar tubes 26 form a connection between the superheater unit 25 and the chamber 19 of the header 1.7 in the smoke box and are disposed Thus it will be seen that the flow of steam from the dome 13 to the cylindersof the locomotive is ber 18, tubes 23, superheater unit 25, tubes 26,

chamber 19, pipe 20, throttle 21 and steam pipes 22. It will be noted in this connection that not nearly so many of the fire tubes of the locomotive are occupied by superheater piping as in the case of the usual fire tube superheater and also that the tubes 23 and 26 are of considerably smaller diameter than the superheater piping of those installations. In this way, the evaporative capacity of the boiler is increased by the use ofmy construction.

Myimproved superheater unit comprises a tortuous metallic conduit 30 which includes the short lengths 31 arranged in parallel relation. to each other and having their adjacent ends alternately connected by means of the integrally formed rcturnbend portions 32. The conduit 30 ispreferably of the same relatively large diameter throughout and is also preferably formed with circular cross section. The ends 33 and 3a of the tortuous conduit f-lll'arc (lisi'iosed at a lower forward position at-ench side of the-firebox and are inwardly turned so as to form the inlet head- 'er 35' and the-outlet header 36 which are disposed in parallel. overlapping relation forwardly of the con volutions 31, 32, of the con- .duit 30.; I The contacting wallsfi? between the parallel lengths 31 of the conduit are welded orotherwise integrally secured together as are also the walls of the return bends 32 and the rear wall of'the outlet header '36 at their points oftangency 38. Suitable connections 39 are provided in the header 85 for the tubes 23 for conveying the saturated steam to the superheater unit. Similar connections40 are provided in the outlet header-36 for the superheated steam conveying tubes 26.

The superheater unit 25. is suppm'ted in the diagonal position illustrated in Figure 1 of the drawings by means of the water tubes 42 which are bent as shown in Figure 2, to connect the side water space 43 oil. the firebox with the front water space 4-4;. A row of refractory fire bricks 45 is disposed'between each of the side margins of the superheatcr unit and the adjacent side sheets of the firebox in order toform an imperforate baille or screen and thereby perform its function as a firebox arch. The triangular orifices 46 formed between the adjacent return bends 32 and the outlet header 36 are also adapted to be stopped by means of arch brick fillers. It will thus be seen that there'is provided, by

means of this invention, a combined locomotive arch and superheater well adapted to fulfill the functions of both of these elements with the attendant savings and increased efficiency which have already been pointed out.

In order to provide for increased conduction of heat from the walls of the superheater unit 25 to the interior core of the conduit 30, for the purpose of more rapidly superheating the steam and of preventing overheating otthe walls, the radiating metal partitions 50 are positioned within the conduit 30. These partitions are preferably diametrically disposed withinthe tubes 31 and the bends 32 and intersect each other at the axes thereof. These vanes or partitions may be inte grally constructed or may be joined by weld ing, and the outer radiating edges of the partitions may be secured integrally or otherwise to the inner Walls of the conduit in any suitable manner. These partitions are disposed only in. the main portion of the conduit 30 and preferably do not extend into the headers 35 and 36, but may be terminated along the diagonal edge lines 51.

It will be readily understood from the disclosures that this partition arrangement divides the conduit 30 into a plurality of separate smaller passageways and eiiectively prevents the presence of a relatively cool core of steam occupying the central portion of the conduits due to the exceedingly low heat conductivity of the steam, which would be the condition present in conduits of such rela'- tively large diameter as the present ones, were these partitions to be omitted.

Thus, by means of my invention, there is provided a combined arch and superheater adapted to be positioned in the firebox of a locomotive and so designed as to be capable of withstanding the extremely high temperatures encountered therein, and adapted, furthermore, to apply a greatly increased degree of superheat to the steam supplied to the cylinders, serving in this way to increase the efficiency of the locomotive to a very large extent.

It is to be understood that various changes and modifications may be made in the embodiment illustrated without departing from the scope oi the invention as defined in the appended claims.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. A locomotive firebox arch comprising a supporting structure of water tubes, a metallic member providing a tortuous steam conduit mounted onsaid structure centrally ot' the firebox, and refractory material disposed around said member to form therewith a substantially gas tight screen.

2. A combined firebox arch and superheater unit comprising a metallic memberproviding a tortuous steam conduit and including a series of parallel tubes integrally united along their contacting walls so as to form a substantially imperforate screen.

3. A locomotive superheater installation, comprising, in combination, a superheater unit disposed in the firebox of the locomotive and comprising a metallic member providing a tortuous steam conduit which terminates in inlet and outlet headers, a superheater header disposed in the smoke box of the locomotive in communication with the steam space of the boiler and with the cylinders of the locomotive, and a seriesof tubes disposed within the fire tubes of the boiler and connecting said inlet and outlet headers of the superheater unit with the superheater header.

4. A superheater unit adapted to occupy a longitudinally inclined position in the firebox of a furnace and. comprising a series of parallel longitudinally disposed tubes having their adjacent walls integrally connected throughout their length and in alternate communication at their ends to provide a tortuous conduit for steam, said conduit termi nating at each end in an inwardly directed extension comprisinga header, said headers disposed in parallel relation and integrally connected along their adjacent walls, the header which is disposed nearer the series of tubes being integrally joined thereto.

5. A combined firebox arch and superheater unit for locomotive boilers or the like,

i comprising a tortuous metallic conduit provided with inlet and outlet headers at the ends thereof, said conduit being of relatively large cross-section and having positioned therein a plurality of radially disposed heat conducting partitions, a superheater header disposed in the smoke box of the locomotive, a plurality of saturated steam tubes connecting the inlet header of said unit with said superheater header and a plurality of superheater steam tubes connecting the outlet header of said unit with said superheater header, said tubes passing through certain of the fire tubes of the boiler.

6. A locomotive superheater installation including, in combination, a combined firebox arch. and superheater unit comprising a metallic member providing a tortuous steam conduit and having its forward edge disposed in contact with the inner throat sheet of the firebox and extending upwardly and rearwardly therefrom, a superheater header in thesmoke box of a locomotive, and a pluralityof connecting tubes disposed within certain of the fire tubes of the boiler and connecting said firebox unit with said header.

JOHN A. MoGRElV. 

